Ecological Fitness of Vibrios and the Emergence of Pathogenic Traits

描述（由申请人提供）：众所周知，获得致病性岛屿（PAIs）有助于环境细菌向致病生物的转化。然而，是什么限制或促进了PAIs在基因相似的菌株中获得，人们仍然知之甚少。o抗原是覆盖在革兰氏阴性菌细胞表面的高度多样化和菌株特异性结构，已被证明在环境中的发病和生存中发挥重要作用。我假设PAIs和o抗原的某些组合在特定（微）栖息地（例如，无脊椎动物肠道，浮游生物，动物表面）中提供了生态适应性优势，并且这使特定的菌株群体倾向于向致病性进化。弧菌是革兰氏阴性菌；某些菌株感染海洋动物和人类宿主。由于弧菌在海洋栖息地大量存在，这些细菌对人类和我国水产养殖业都构成了持续的威胁。因此，有必要探测海洋环境，因为海洋环境可能是新出现病原体的储存库，以便监测这些细菌种群并预测潜在的大流行。波尔兹实验室已经从确定的海洋栖息地中分离出数千种微多样性弧菌。这种菌株收集是同类中最独特的，是研究致病性出现的极好方法。我的研究将利用这些收集，以及从不同海洋栖息地分离的其他弧菌：(i)基于核心基因微多样性，使用MLSA和系统发育方法表征弧菌亚群；（ii）确定PAIs和毒力基因在这些环境弧菌中发生的频率。将利用生物信息学方法从已发表的基因组中鉴定出的已知弧菌毒力位点和其他Ioci开发探针；这些探针将用于使用PCR和Southern blotting技术寻找毒力遗传元件，（iii）确定o抗原多样性与毒力位点共存的水平及其与特定环境的相关性。wb*区编码帮助组装o型抗原的基因；该区域将被分离并测序，以表征这一遗传多样性位点。毒力位点和wb*区域的频率和组合将有助于确定某些环境是否为病原体的滋生地。病原体感染特定的宿主并引起疾病。这项工作的意义在于确定不同的海洋环境是否是对人类和商业水产养殖构成威胁的新出现病原体的储存库。结果可能导致如何监测和预测细菌爆发的见解。

DESCRIPTION (provided by applicant): It is well established that the acquisition of pathogenicity islands (PAIs) assists the transformation of environmental bacteria to disease causing organisms. Yet, it remains poorly understood what limits or promotes the acquisition of PAIs among genetically similar strains. The O-antigen is a highly diverse and strain-specific structure covering the cell surface of Gram-negative bacteria that has been shown to play important roles in both pathogenesis and survival in the environment. I hypothesize that certain combinations of PAIs and O-antigens provide ecological fitness advantages in specific (micro) habitats (e.g., invertebrate guts, plankton, animal surfaces) and that this predisposes specific groups of strains to evolve towards pathogenicity. Vibrios are Gram-negative bacteria; certain strains infect marine animal and human hosts. Because Vibrios are abundant in marine habitats, these bacteria present ongoing threats to both humans and our national aquaculture. Thus, it is necessary to detect marine environments, which may be reservoirs for emerging pathogens in order to monitor these bacterial populations and predict potential pandemics. The Polz laboratory has isolated thousands of microdiverse Vibrios from defined marine habitats. This strain collection is the most exclusive of its kind and presents an excellent means to investigate the emergence of pathogenicity. My research will utilize this collection, as well as other Vibrios isolated from different marine habitats to: (i) characterize subpopulations of Vibrios based on core gene microdiversity using MLSA and phylogenetic approaches, (ii) determine the frequency that PAIs and virulence genes occur in these environmental Vibrios. Probes will be developed from known Vibrios virulence loci and other Ioci identified from published genomes using bioinformatics methods; these probes will be used to find virulence genetic elements using PCR and Southern blotting techniques, (iii) determine at what level O-antigen diversity co-exists with virulence loci and their correlates to specific environments. The wb* region encode genes that help assemble the O-antigen; this region will be isolated and sequenced to characterize this genetically diverse locus. The frequency and combination of both virulence loci and the wb* region will help determine if certain environments are breeding ground for pathogens. Pathogens infect particular hosts and cause disease. The relevance of this work is to determine if different marine environments are reservoirs for emerging pathogens that pose threat to both humans and commercial aquaculture. Results may lead to insights on how to monitor and predict bacterial outbreaks.